fix: restore bucket breadcrumb click navigation

[cxymds]

Summary

• Render breadcrumb links directly through BreadcrumbLink instead of nesting Next Link via Base UI render.
• Keep breadcrumb clicks routed through router.push so bucket detail pages can return to the bucket list after refresh.
• Add a source regression test to prevent reintroducing the broken composition pattern.

Fixes rustfs/rustfs#3403

Test Plan

• node --test tests/lib/top-nav-breadcrumb-source.test.js
• COREPACK_ENABLE_PROJECT_SPEC=0 pnpm lint
• COREPACK_ENABLE_PROJECT_SPEC=0 pnpm tsc --noEmit